The invention relates to a mobile communication system which is arranged to broadcast general information on a cell broadcast channel of a base station, and to a mobile station.
Various service announcements can be transmitted to mobile stations on the basis of a service request of a subscriber in mobile communication systems. Generally, these chargeable services are most often arranged to be provided from outside the actual mobile communication system. By making a call to a required service number, a mobile subscriber is able to order a selected service announcement to be delivered to the display of the mobile station, for example. Of these individual services e.g. weather forecast, traffic announcements, local news and other local services, such as taxi ordering and service station announcements and so on are services where the mobile subscriber selects the desired announcement on the basis of the geographical area. The mobile subscriber generally wishes to have the service announcement related to his/her current location which varies because of the mobile nature of the mobile subscriber.
In the new European digital GSM mobile communication system, it is also possible, in addition to speech and data connections established on normal traffic channels, to send short digital data messages, called short messages, in the control or signalling channels of the system along with the actual signalling. The GSM mobile network is connected to a separate short message service centre SMSC which thus establishes a connection between a specific short message network and the GSM network. The short message service centre SMSC located outside the mobile network transmits short messages to mobile subscribers and from a mobile subscriber (A subscriber) to another mobile subscriber (B subscriber) or to any unit capable of receiving short messages outside the mobile network. The subscriber inputs a short message to be sent by the keyboard of the mobile station or by a computer connected to the mobile station. The mobile station sends the short message on the control or signalling channel to the base station from which the short message is further transferred via the mobile switching centre to the short message service centre SMSC. The service centre SMSC forwards the short message to the short message network. Correspondingly, the short message service centre SMSC transmits mobile-terminating short messages on the control or signalling channel.
The short message facility has been utilized in services provided for mobile subscribers. One short message service is the sea weather forecast service maintained by the Meteorological Office in Finland. A mobile subscriber makes a call to the telephone number of the sea weather forecast and indicates the geographical area from which the weather information is wished to be known. The subscriber interrupts the connection to the service number and after a while receives the required weather information as a short message which is displayed on the display of the mobile station. As weather information is permanently associated with a geographical area, in the sea weather forecast service the Finnish sea area is divided into eleven areas from which the subscriber can select the desired one by dialling the telephone number of the respective area. A problem with the above-described selection of the geographical area of the service is that the geographical areas are rather large in order to avoid a too long selection list, wherefore the service announcement has to be formed to be general to cover the whole selected large geographical area. In some services, such as in the short message service informing of traffic jams, in order that the service announcement is useful, it is required that the service can be focused accurately to the rather small geographical area requested by the subscriber. Furthermore, the problem with the prior art short message service described above is that the subscriber is not able to request the service without setting up a mobile speech connection on a normal traffic channel for making it possible to inform the subscriber in real time of the selection alternatives of the geographical area.
FIG. 1 shows a simplified block diagram of the pan-European GSM mobile communication system. The mobile station MS is connected via the radio path to one of base transceiver stations BTS, such as the base station BTS1 in FIG. 1. The base station system BSS comprises a base station controller BSC and base stations BTS controlled by the BSC. Usually several base station controllers BSC are controlled by a mobile services switching centre MSC. The mobile services switching centre MSC is connected to other mobile services switching centres. Via a gateway mobile services switching centre (GMSC) the GSM is connected to other networks, such as the public switched telephone network PSTN, to a public land mobile network PLMN, to an integrated services data network ISDN or to a service centre SC, such as the short message service centre SMSC. The operation and maintenance centre OMC monitors the operation of the whole system. The subscriber data of the mobile station MS is stored permanently into a home location register HLR and temporarily into a visitor location register VLR in the area of which the mobile station MS is located at the time. The location information of the mobile station MS is stored into the visitor location register VLR at the accuracy of the location area LA. The geographical area monitored by the visitor location register is divided into one or more location areas LA. One or more base stations BTS can operate in each location area.
The base stations BTS continuously broadcast information on a broadcast channel about themselves and their environment, such as a base station identity code BSIC, adjacent cell information and a location area identifier LAI broadcast on a paging channel. The cell broadcast centre situated at the base station controller BSC, for example. manages the messages of the cell broadcast channels of the base stations BTS. The cell broadcast centre transmits via the base station controller BSC the broadcast messages assigned for each individual base station BTS on the basis of initial information supplied by the operator. The broadcast on paging channels and cell broadcast channels, for example, has no address nor is encrypted but intended to be received by all mobile stations MS within the geographical area covered by the transmission of the base station. For a more detailed description of cell broadcast, reference is made to GSM recommendation GSM 03.41 xe2x80x9cEuropean digital cellular telecommunication system (Phase 2); Technical realization of Short Message Service Cell Broadcast (SMSCB)xe2x80x9d.
FIG. 2 shows a signalling diagram of a prior art transfer of a short message from a short message service centre SMSC to a mobile station. The SMSC sends a short message to the GMSC of the GSM network via a transit network, when required (message 1). The GMSC inquires the location of the mobile station from the home location register HLR of B subscriber (message 2). In message 3, the HLR returns to the GMSC information indicating the visitor location register VLR in whose area the mobile station of B subscriber is situated. The GMSC sends a short message further to an MSC according to the address of the VLR (message 4). When the short message is received by the MSC, the MSC inquires by message 5 from the VLR routing information for the short message. The VLR responds to the inquiry by sending to the MSC routing instructions for the location area LA indicated by stored location information of the mobile station of B subscriber (message 6). The MSC sends a short message to the mobile station MS of B subscriber via the base station controller BSC and the base station BTS (message 7). The short message travels transparently through the mobile network from the SMSC to the mobile station MS.
FIG. 3 shows a signalling diagram of a prior art transfer of a short message in the opposite direction, that is, from the mobile station MS to the short message service centre SMSC. In message 31 the mobile station MS sends a connection request to the base station BTS, and after having received a response, sends a short message via the base station BTS and the base station controller BSC to the MSC (message 32). In message 33 the MSC sends a short message to the gateway MSC which forwards the short message via the transfer network, when required, to the SMSC (message 34). From the SMSC the short message is delivered to the addressed receiver.
An object of the present invention is to provide universally intelligible location information in a mobile communication system for use as a parameter for an application dependent on the geographical area.
This new way of providing location information for an application is attained with the method comprising a step of receiving a broadcast signal on a cell broadcast channel of a base station by a mobile station. The method is characterized by the steps of broadcasting location information identifying the geographical location on the cell broadcast channel of the base station, and utilizing this location information in an application dependent on the geographical location.
The invention further relates to a mobile communication system where a base station is arranged to broadcast general information on a cell broadcast channel and a mobile station is arranged to receive on a cell broadcast channel of a base station. The system is characterized in that the mobile communication system is arranged to broadcast location information identifying the geographical location on the cell broadcast channel of the base station, and to utilize this location information in an application dependent on the geographical location.
The invention further relates to a base station comprising at least one cell broadcast channel for broadcasting general information to mobile stations within a coverage area of the base station. The base station is characterized in that the base station is arranged to broadcast on the cell broadcast channel location information identifying the geographical location.
The invention is based on the idea that the base stations broadcast continuously on their cell broadcast channel location information which is received by the mobile station and utilized in an application dependent on the geographical location.
The base station of the invention broadcasts on the cell broadcast channel location information, such as the co-ordinates and place name of the base station site. The mobile station of the invention receives a broadcast and picks the location information from the transmission. The location information is then used as a parameter in an application which is dependent on the geographical location. In a preferred embodiment of the invention, when the mobile subscriber wishes to request a service which is dependent on the geographical area, such as a service announcement from a service unit of the public switched telephone network, for example, the mobile subscriber provides a service request, in the form of a short message, for example, and attaches the picked location information to this service request. The mobile station sends a service request via the mobile network to the service unit, such as a short message to the short message service centre from which the short message is forwarded to the required service provider. On the basis of the location information included in the service request, the unit providing the service selects the service requested by the subscriber, such as a service announcement, and sends this service announcement to the mobile subscriber to the mobile network, such as a short message via the short message service centre.
An advantage of the mobile communication system is that the location information to be processed is already in an universally intelligible format.
A further advantage of the mobile system of the invention is that the mobile subscriber need not determine the geographical area he/she is located in when ordering the service.
Still another advantage of the mobile communication system of the invention is that the service request can be sent in a short message, for example, as the delivery of the request does not require transmissions in two directions.
Furthermore, the mobile communication system provides the advantage that it will be easier and faster to request services dependent on the geographical location, such as service announcements, in comparison with a prior art implementation.
An advantage of the method of the invention is that a service announcement can be made to cover only a small geographical area.